Crop drying type air heater



July 22, 1952 A. A. ANDERsr-:N ETAL cRoP DRYING TYPE AIR HEATER 2 SHEETS-SHEET l Filed Jan. 21, 1949 6 2 A v m3,@ im .w www y aww i w, i l@ a Af .R E 0V www a A. A. ANDERSEN El AL CROP DRYING TYPE AIR HEATER July 22, 1952 2 SHEETS-SHEET 2 Filed Jan. 2,1. 1949 Patented July 22, 15952 CROP DRYING TYPE AIR HEATER Y Arthur A. Andersen, Crystal Lake, and Bernard C. Mathews, Cary, ill., assignors to American Crop-Drying Equipment Company, Crystal Lake,vlll., a corporation oi Illinois Application January 21, 1949, Serial No. '71,834

Our invention relates to an air heater of a type suitable for crop drying and has reference more particularly to a heater having one or more oil or gas burners enclosed in a casing through which air is circulated by a blower and mixed with the products of combustion to provide the vdrying medium.

For crop drying and other similar purposes, it is desirable to supply a large volume of heated air, for rapid drying, and under suiicient pressure to insure circulation thereof through a substantial batch of the material to be dried.

Such driers must be economical, to minimize the cost of drying, and they must be simple and convenient to operate, so that they are readily and safely usable by the ordinary purchaser without requiring special skill or training. They must also be reliable, so as to avoid delays or interruptions in drying, and it is desirable that they be of a -compact and portable nature so that they are readily transportable from place to place.

The principal objects of our invention are to provide an improved heater of a type suitable for crop drying purposes; to provide a construction which is particularly simple, compact and reliable and which is readilyyoperable by the ordinary purchaser; to insure high eilciency and economy of operation; and to permit convenient regulation of the amount of heat, these and other objects being accomplished as pointed out more fully hereinafter and as shown on the accompanying drawing, in which:

Fig, 1 is a view of the'y discharge end, hereinafter referred to as the front, constructed in accordance withl our invention;

Fjig. 2 is a View of the other end thereof, hereinaiter referred to as the rear end;

Fig. 3 is an enlarged view, similar to Fig. 2, but with the rear end wall of the heater removed, said View being taken substantially on the line 3*-3 of-Fig. 4; and

Fig.` 4 is aview partly in longitudinal section and with other parts broken away to disclose details of the construction, said view being taken substantially on the line 4-'4 of Fig; 3'.v

, In `the drawings, the reference numeral il) indicates the casing of the heater, said casing being preferably ofthe form shown with abottom wall I I, semi-circular top wall I2 having the sidewalls i3 continuing downwardly therefrom to the -bottorn1 Wall, and front and rear end walls I4 ,and I rrespectvely, the former of which is lined with refractory I6. on skids 6L- v ,.'lhefront wall lll-oi the casingis'provided withH Preferably the heater is mounted 3 Claims. (C1. 26S-i9) a large opening' i1 which is concentric with the semi-circular top wall l2 and-surrounded by an annular ring or shell iS with ila-red inner end in which is located a propeller i9, preferably six bladed, which is rotated in a direction to` ex'- haust air from the interior of the casing through the opening Il.

rlhis propeller is secured to a shaft 20 which is mounted in bearings 2| on a platform 22 carried by a frame 23 which is secured to t-he frcntwal1 of the heater casing. A power source, for example, an electric motor 24, is mounted on a platform 25 on the top of the heater` casing and is connected by a belt 2E through an opening in the easing top Walll, to a pulley 21 on the propeller shaft 2G for operating the propeller I9.

One or more combustion chambers, each with a separate burner, are located in the bottom of the heater casing, two being shown in the illustrated structure respectively at 28` and 29v and each has a separate oil burner 3B. These combustion chambers are alike and each is of elongated'cylindrical form, closed at the rear end by a rear end wall 3l and supported near the rear end by an' upright cradle plate 32 to which the chamber is secured by an overlying arcuate clamping bolt 33.

` At the front end each cylindrical chamber 28 andfE is-secured to a panel 34 which rests' on the 'bottom wall Il of the heater casing and is provided witha circular opening, smaller than and concentric with the respective cylinder 28 or 29, and a cylindrical sleeve 35 is secured at its rear end in said circular opening and at its front end is secured to the margin of a corresponding circular opening 36 in the front wall I4 of the heater casing.

A -burner 30 is located centrally in therespective cylindrical sleeve herein, and extends inwardly from the heater casing front wall |4- to a partitionl 3l, which is spacedforwardlyv from the front end of the respective combustion chamber, and provided with a central opening 38 with a ceramic ring 39 prolv jecting rearwardly therearound into the respective combustion chamber 28 or 29 and provided with a rearwardly flaring opening as shown in Fig. 4.

Each burner 30 is of gun type with an air supply tube 40 containing an oil supply nozzle 4| at y the'inner'end thereof with a pair of igniting electrodes 42 having a spark gap therebetween directly beyond the nozzle 4I, the tube 40' preferably being provided in a conventional manner with spiral ns around the nozzle 4| to whirl the 35, oil burners being shown` air entering through the air tube 40, and the inner end of the tube 40 also being contracted as illustrated, to deflect the air inwardly at the inner end of the nozzle 4 I.

The outer end of the air tube 4l) is secured to a duct 43 which is secured to the front wall I4 of the heater casing and extends upwardly to the air discharge opening I1 where it has an air scoop 44 lwithin the opening I1 at the periphery thereof and opening rearwardly as shown in Fig. 4 so that the fan I9, when in operation, forces a blast of air into the scoop end 44 of the duct 43. This duct 43 is closed at the lower and and communicates with the outer end of the air tube 40 so that the air forced into the tube 43 by the fan I9 is discharged through the rear end of the tube 40 around the nozzleAI and constitutes the primary air supply for supporting combustion.

The rear end of the air tube 40 terminates at and is smaller than the opening 38 of the partition 31 to leave an annular space 45 around the air tube for secondary air supply, and the opening 38 in the front wall I4 of the casing is provided around the tube 4D with a screen 46 which freely admits air therethrough. Thus, when the burner is in operation and a blast of air supplied through the air tube 40 from the fan I9, the discharge from the tube 40 through the flared opening of the ceramic ring 39 tends to draw in a secondary supply of air through the annular opening 45, this tendency being also supplemented, as hereinafter explained, by the fan I9 which serves to exhaust the products of combustion from the combustion chambers 28 and 29. For regulating the supply of air entering the scoop inlet 44, a damper 41 may be provided therein and secured, as at 48, to the wall of the scoop, remotely from the fan I9, in a springy manner to be biased toward the top wall of the scoop and the damper may be adjusted by the screw 49 to vary the size of the opening int-o the scoop.

For supplying fuel to the nozzles 4I a pump 50 is suspended from the platform 22, which supports the fan, and is driven by the belt 5I from the fan shaft. This pump has a pipe 52 leading thereto from a source of oil supply and has pipes 53 leading therefrom to the burner nozzles 4I, each pipe 53 having a valve therein with an operating handle 54 by lwhich to regulate the supply of oil to the respective nozzle. The electrodes 42 have conductors 55 leading therefrom to a suitable source of electrical energy for igniting the burners.

Each combustion chamber 28 and 29 has a large duct 55 leading upwardly therefrom at the rear end and extended forwardly, as indicated at 51, to the fan I9 where each duct has an open end and preferably at diametrically opposite sides thereof respectively as shown in Figs. 1 and 3.

Preferably a screen 58 is provided in each duct 56 near the combustion chamber to serve as a spark arrester and the forwardly extending portion 51 of each duct is provided with a damper 59 therein operable by a handle B0 at the exterior of the respective side of the casing.

The rear wall I5 of the heater casing is provided with a large opening therethrough directly behind the fan I9 and containing a screen 63, for supplying air said wall also has an opening therethrough directly behind each combustion chamber 28 and 29 and each provided with a screen 62.

Each burner may be regulated by its respective oil supply valve 54 to vary the amount of heat produced thereby, and the amount of air supplied through each burner tube 40 may be regulated by the damper valve 41. Moreover, the amount of air supplied to the burner may be further regulated by adjusting the damper 59 of the respective combustion chamber to vary the suction created by the fan in the respective duct 51. Either damper 59 may be closed entirely if the respective combustion chamber is not being used.

The oil burners of the two combustion chambers 28 and 29 may be of the same capacity or, if desired, one may be of larger capacity than the other, and either one of the burners may be operated alone, or both may be operated simultaneously, depending upon the amount of heat required for the particular operation.

Thus, in the operation of the above heater the fan I9 draws air through the screened openings 63 and 62 which is heated within the casing I0 by the heat from the combustion chambers 28 and 29 and of the ducts 56, 51 leading therefrom and discharges the thus heated air through the discharge opening I'I from the casing.

Moreover, said fan also exhausts the gaseous products of combustion from the combustion chambers 28 and 29 and discharges these products through the fan with the heated air from the interior of the casing, thereby thoroughly commingling said combustion products with the air and providing a large volume of highly heated gaseous medium for drying purposes.

This same fan also furnishes the primary supply of air through the duct 43 for combustion, which air supply may be regulated by the damper 41 in the air scoops 44, and moreover the fan also, through its suction effect in the ducts 56, 51, which may be regulated by the dampers 59, assists in the primary supply of air through the burner` tubes 40 and contributes materially to theintake of secondary air through the screened opening 46.

As a result of these multiple functions per formed by the fan a particularly simple, efficient and dependable heater is provided and in a particularly compact form and with convenient adjustability whereby a wide range of heat is available and with complete combustion assured.

While we have shown and described our invention in a preferred form, we are aware that changes can be made therein without departing from the spirit of our invention, the scope of which is to be determined by the appended claims.

What is claimed is:

l. In a heater of the class described, the combination of a housing which encloses an air circulation compartment, said housing having an air inlet opening through an outer wall thereof and an air outlet opening through an outer wall thereof at a place remote from said air inlet opening, a fan at said outlet opening and operable to circulate air through said air circulation compartment from said air inlet opening to said air outlet opening and vto discharge same through said air outlet opening, a casing within said air circulation compartment having a combustion chamber therein, a burner through which a combustible mixture of fuel and air is suppliable. said burner being mounted to discharge the combustible mixture therefrom into the combustion chamber, and anexhaust duct which leads from said `combustion chamber to the low pressure side of said fan and provides a path of circulation which leads from the combustion chamber to the fan and is separate from and located in the path of circulation from said air inlet opening tojsaid air outlet opening, said exhaust duct having the outlet therefrom immediately proximate to and facing toward the intake side of the fan.

2. In a heater of the class described, the combination of a housing which encloses an air circulation compartment, said housing having an air inlet opening through an outer Wall thereof and an air outlet opening through an outer wall thereof at a place remote from said air inlet opening, a fan at said outlet opening and operable to circulate air through said air circulation compartment from said air inlet opening to said air outlet opening and to discharge same through said air outlet opening, a casing within said air circulation compartment having a combustion chamber therein, a burner through which a combustible mixture of fuel and air is suppliable, said burner being mounted to discharge the combustible mixture therefrom into the combustion chamber, an exhaust duct which leads from said combustion chamber to the low pressure side of said fan and provides a path of circulation which leads from the combustion chamber to the fan and is separate from and located in the path of circulation from said air inlet opening to said air outlet opening, said exhaust duct having the outlet therefrom immediately proximate to and facing toward the intake side of the fan, and an air duct which leads from the discharge side of said fan to the burner and supplies the air of the aforesaid combustible mixture, said air duct having the inlet opening thereof immediately proximate to and facing toward the discharge side of said fan.

3. In a heater of the class described, the combination of a housing which encloses an air circulation compartment, said housing having an air inlet opening through an outer wall thereof and an air outlet opening through an outer wall thereof at a place remote from said air inlet opening, a fan at said outlet opening and operable to circulate air through said air circulation compartment from said air inlet opening to said air outlet opening and to discharge same through said air outlet opening, a casing within said air circulation compartment having a combustion chamber therein, a burner through which a combustible mixture of fuel and air is suppliable, said burner being mounted to discharge the combustible mixture therefrom into the combustion chamber, an exhaust duct which leads from said combustion chamber to the low pressure side of said fan and provides a path of circulation which leads from the combustion chamber to the fan and is separate from and located in the path of circulation from said air inlet opening to said air outlet opening, said exhaust duct having the outlet therefrom immediately proximate to and facing toward the intake side of the fan, an air duct which leads from the discharge side of the fan to the burner and supplies the air of the aforesaid combustible mixture, said air duct having the inlet opening thereof immediately proximate to and facing toward the discharge side of the fan, said combustion chamber having an air opening leading thereinto from the exterior of the housing and surrounding the burner through which the combustible mixture is supplied.

ARTHUR A. ANDERSEN. BERNARD C. MATHEWS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,629,253 Breese Nov. 9, 1926 1,778,146 Davis Oct. 14, 1930 2,066,524 Gehnrich Jan. 5, 1937 2,164,954 Stephens July 4, 1939 2,171,275 Morrison Aug. 29, 1939 2,174,251 Williams Sept. 26, 1939 2,242,802 Stramaglia May 20, 1941 2,397,012 Jepson Mar. 19, 1946 2,397,171 Troller et al. Mar. 26, 1946 2,418,097 Ruff Mar. 25, 1947 2,454,296 Woods Nov. 23, 1948 

